The invention relates to a method for establishing a video telephone connection in a data network comprising a telephone network and an IP network based on the Internet Protocol. The expression video telephone connection is to be understood generally here and in the text below, and encompasses multimedia telephony in addition to pure video telephony.
To transmit multimedia data, it is known from the related art to connect a telephone network, for example a mobile radio network, in particular a GSM or UMTS mobile radio network, to an IP-based network, in order to perform voice and video telephony effectively over such a combined data network. It is necessary to ensure in this case that the services of the telephone network interwork with the services of the IP network, and in particular that conversion of the signaling used and of the transport format of the payload data is ensured.
In the field of 3GPP networks (3GPP=3rd Generation Partnership Project), the 3GPP Standard TS 29.163 specified an interworking between a so-called CS telephone network (CS=Circuit Switched), in particular a 3GPP CS domain or a PSTN network (PSTN=Public Switched Telephone Network), and an IP-based IMS network (IMS=IP Multimedia Subsystem). However, the specification relates purely to voice telephony, and no method of effectively establishing a video telephone connection between a CS network and an IMS network (IMS=IP Multimedia Subsystem) is known.